Neon-tube.



G. CLAUDE.

Patented July 4, 1916.

INVf/V TOR ATTORNEY n1 mm ml" emu-0mm, rump-awn. n c

GEORGES CLAUDE, 0F BOULOGNE-SUR-SEINE, FRANCE.

NEON-TUBE.

Specification of Letters Patent.

Patented July 4, 1916.

Application tiled February 12, 1915. Serial No. 7,913.

'1 'u all whom it may concern:

lie it known hat I, (lemmas CnAUoa, a citizen of the Republic of France,and resident of Boulogne-sur-Seine, France, have lilvented new anduseful improvements in or Relating to Neon-'lubes, which improvementsare fully set forth in the following specification.

It is well known now that the maximum degree of luminosity which neonpossesses can only be obtained in the lighting tubes if the gas is in ahighly pure condition. According to a known process, this hi"h degree ofpurity may be obtained by providing the tube with one or morereceptacles containing charcoal; and when the tube has been freed fromits impurities by the action of vacuum and current, and then has beencharged with noon to the desired de ree and sealed, the receptacle, orreceptaaes, are plunged into liquid air and a current passedtherethrough. Under these conditions, and owing to diffusion, all theimpurities freed by the passage of the current between the electrodes,are gradually deposited upon the charcoal, and, after a greater or lesslength of time, the tube is finally completed. Now diffusion, however,acts very slowly, and this slowness increases rapidly when the pressureincreases and the diameter of the tubes decreases. Forming a tube havinga diameter of 7 millimeters and charged with neon under a pressure of 10millimeters in cold condition, is practically impossible.

The present invention has for its object to im )rove these conditions offormation, by completing or replacin the action of the diffusion bybodily, an repeatedly dis lacing the atmosphere of the tube towar thepurifying chambers or receptacles.

By using charcoal receptacles having a capacity such that the quantityof neon inclosed therein represents several times the quantity containedin the atmosphere of the tube, and by passing the current throughintermittently, the results will be improved considerably, because underthese conditions the heating and the cooling of the gas in the tubebring about a very appreciable respiration, so to speak, between thetube and the charcoal, and conversely. This method, apart from the factthat the gaseous displacement afi'ects each time only a fraction of theatmosphere, has the drawback that since the impurities are liberatedonly upon the passage of the current, the portion of the atmospherewhich is driven back is almost pure neon, while the impuritiesaccmnulatc ill the remaining portion. This method, although adequate fortubes having a large diameter, is not sulliciently rapid for smalltubes. This is particularly true in the frequently occurring case wherethe passage of t 10 current, notwithstamling a very strong treatmentbefore the charge of neon, liberates considerable qnantitics ofimpurities, producing a blue light whose spectrum has a luminous basewinch shows, in addition to the hydrogen lines, certain special linesthe easiest to be observed being 516.5 line. In this case, and withtubes having a diameter of 6 or 7 millimeters, the formation may beprolonged to a very great extent in spite of the use of a plurality ofcharcoal receptacles, and thus involves an expenditure of current andliquid air, storage of material, and considerable expense incurred forsupervision.

According to a more effective method, diffusion is completely abandonedas a means for the transport of the gaseous molecules; and the passageof the current is no longer relied upon to convey the impurities towardthe purifying chamber, but is employed solely for liberating theimpurities. In this case, the tubes, previously charged with the desiredquantity of neon, are formed by exclusively utilizin physical ormechanical means which permit the rapid displacement of the entireimpure gaseous contents of the tube, instead of merely a small portionthereof, as aforesaid, toward the purifying chamher, and conversely. Thepurifying chamber or chambers will most frequently com rise a receptacleor receptacles made of cold charcoal, but they may also contain suitablechemical re-agents such as magnesium, lithium, either heated or not, andso on. The entire impure atmos here thus comes into contact with thepuri ving material, is freed from its impurities t iercat, and returnsin a purified condition to the tube where it is again charged withimpurities, under the action of the current; and the cycle is completed.These steps may be carried out as rapidly as desired, the formation ofthe smallest tubes under the highest pressure being thus rendered veryrapid. s will be explained hereinafter, it is even possible to create inthe tube a real circulation extending over several times the capacity ofthe tube and dealing only with the previously-charged gases, because noextraneous gases can be introduced since'there is no communication withthe outside atmosphere.

In the accompanying drawings Figs. 1 to 5 show several ways in which theprocess according to the present invention may be carried out.

One method of carrying these displacements of the impure atmosphere intoeffect may be realized, as indicated in Fig. 1, by )roviding a source ofcold more intense than liquid air such as, for example, liquid hydrogen.The tube T to be formed is provided with the charcoal receptacle R, andis subjected as usual to the action of the vacuum and current, and thencharged with such a quantity of neon that after immersion in liquid air,the ressure will be adequate. Current is again passed through, as soonas possible; and when the gas has again become impure, the-vessel Vfilled with liquid hydrogen is substituted for the vessel V filled withliquid air in which the charcoal receptacle is immersed. The gas is thenrapidly absorbed and when, in turn, liquid nitrogen is substituted forhydrogen, pure neon is evolved, while the impurities remain in thecharcoal. After the oieration has been repeated a suilicient num er oftimes, the tube is formed and may be separated from the charcoal.

No liquid hydrogen is required to establish a circulation of pure neonthrough the tube, as this has been rendered possible for .the fol owingreasons:-It has been observed that at the temperature of liquid oxygen,the charc al can still retain with a suiiicient tenacity, the impuritiesfreed when the tube is treated; for instance, hydrogen hydrocarbons andthe like. The quantity 0 neon which the charcoal can retain at a g venpressure, however, is about three times less than that atthe temperatureof liquid nitrogen. One way of utilizing this property, consists asshown in Fig. 2, in providing the tube to be formed with two charcoalreceptacles R, R located at its ends. The tube is purified by thevacuum'pum and current, then char ed with neon to the desired extent andc osed, and then one of the rece tacles is plunged into liquid oxygenand t e other into liquid nitrogen. After a few mo- 'ments', thepositions of the two receptacles are very ra idly reversed, anadditional re ceptacle of iquid being used if necessary, in order toeffect the substitution. A considerable quantity of pure neon is evolvedin the tube, and moves from the oxygen to the nitrogen; then the currentmay immediately be passed through to free the impurities. Thereceptacles are again reversed, the circulation taking place in theopposite direction, and so on until urificatmn is completed. In eitherof t ese methods, it is obvious that other cold-producingmaterials maybe used.

The charges of neon may be cil'ected when the charcoal receptacles arealready immersed in the liquid air, (Fig. 3); and in this case, it isadvisable that the gas should be introduced by a suitable pipe t throughthe bottom of the receptacle, so as to traverse the cold charcoal andgive oli' its impurities beforerreaching the tube. Owing to thisarrangement, no disturlmnccs are caused by air entering through valvesor the gage, should the latter be lllltilltitlllet'l on the tube untilentirely isolated. The above-described physical means for displacing thegaseous atmosphere may be replaced by suitable mechanical meanscombined, if necessary, with a chemical purifying means.

Fi 4 illustrates one way in which a proc- 058 similar to the li uidhydrogen process above-described, can )0 carried into effect. Bylowering the container B, the sphere C is emptied of its mercury, thecapacity of this sphere being large relatively to the volume of aircontained in the tube T. This air is therefore caused to traverse thechamher or s ace D filled with suitable purifying materia s, such ascold charcoal orcalcium, lithium and the like, either heated or not. Thecontainer B being then raised, pure ncon is discharged into the tube,and the operation is repeated a suiiicient number of times to insurepurification.

Finally, Fig. 5 also shows by way of example, how mechanical means maybe used in a process similar to those carried-out with liquid oxygen andliquid nitrogen.

The mercury containers B and B secured to the two ends of the tube A aresuitably operated in opposite directions so as to create a vacuumalternately in one of the spheres O and C, while compression takes p acein the other. The impure gas of the tube is thus caused to circulatealternately in the tube from one to the other of the purifying chambersD and D, so that the tube is rapidly formed. The tubes A illustrated inFigs. 4 and 5, may be made of rubber and provided with stop valves X forthe purpose of maintaining the level of the mercuryafter each operation.

Claims:

1. A process for forming luminous neon tubes partially purified byvacuum and by an electric current and previously charged with the reuired amount of neon, essentlallv consisting in displacing the entirepollute atmosphere of the tube by using means other than the electriccurrent, the

displacement taking place toward a purifying chamber connected to thetube. isplacm the purified atmosphere from the purify ng chamber towardthe tube to he formed, liberating the fresh impurities under the actionof the electric current, repeating the above-described displacementsuntil the tube is entirely formed, and then separating the purifyingchamber from the formed tube.

2. A process for forming luminous neon tubes partially purified byvacuum and by an electric current and previously charged with therequired amount of neon, essentially consistm in securin a charcoalpurifying receptac e to the tu e, absorbing the entire atmosphere of thetube by immersing the purifying receptacle in a bath of liquid h drogen,displacing the purified atmosp ere again by immersing the saidreceptacle in a bath having not so low a temperature, setting furtherimpurities free by means of an electric current, repeating theabove-described immersions alternately until the tube is entirelyformed, and then separatin the purifying chamber from the forms tube.

3. A process for forming luminous neon Copies of this patent me, be

tubes partially purified by vacuum and by an electric current andpreviously charged with the required amount of neon, essentiallyconsistm in connectin each end of the tube to a c arcoal purifyingreceptacle, alternately dipping one of the receptacles in liquid oxygenand the other in liquid nitrogen, displaeing the impurities set free bythe current toward the coldest receptacle, repeatin the above-describedimmersions alternate y until the tube is entirely formed, and thenseparatin the purifying chamber from the formed tu e.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

GEORGES CLAUDE. Witnesses:

ELITE Lnnou'r, DE W. O. POOLE, Jr.

Wsshls'tos, D. O.

